It is common practice in the production of plastic parts and the like to first design the part and then painstakingly produce a prototype of the part, each step involving considerable time, effort, and expense. The design is then reviewed, and often times the process is repeated until the design has been optimized. After optimization, the next step is production. Most production plastic parts are injection molded. Since the design time and tooling costs are very high, plastic parts are usually practical only in high-volume production. While other processes are available for the production of low-volume plastic parts, including direct machining, vacuum forming, direct forming, and compression molding, these methods are typically only cost effective for short run production and the parts produced are usually inferior in quality to injection molded parts.
Plastic parts possess many advantages including light weight, low cost, electrical resistivity, and resistance to many chemicals. However, in many cases, the physical properties of the plastic part are not sufficient for the intended application and an insert made from another material such as metal (to provide additional properties not inherent to the plastic, such as conductivity) is often placed in the part. The use of inserts in injection molding is well known to those skilled in the art. It can therefore be appreciated that using these types of inserts is an expensive and cumbersome process because the inserts must be carefully placed in the mold prior to each molding cycle. Injection molded parts having inserts are much more expensive than parts without inserts because of the additional labor involved and the increase in cycle time of the molding process. In addition, the tooling required to accommodate structural inserts in both injection molding and vacuum forming systems is much more complicated and expensive.
Hence, there continues to be an existing need in the design and production of plastic parts for an enhanced capability to rapidly and reliably move from the design stage to a prototype stage and to ultimate production of plastic parts having inserts. Accordingly, those concerned with the production of these types of three-dimensional objects have long recognized the desirability of a system or a method that would provide a rapid, reliable, economical, and automatic means to quickly move from the design stage to a prototype or low volume production stage of parts having inserts. The present invention clearly fulfills all of these needs.